it's not "no reason" it was because daylight saving time changes the timestamp of files by -1 hour. You can recreate this by using a 'touch' utility to change the timestamp on any of your scripts or ini's.

In remote editor, if you uncheck options/"monitor file changes" you won't see that.

As for the tm_ that is unrelated. That is a temporary filename that mirc uses to make file changes, then replaces on top of the original file.